In electrostatographic printing, commonly known as xerographic or printing or copying, an important process step is known as “fusing”. In the fusing step of the xerographic process, dry marking material, such as toner, which has been placed in imagewise fashion on an imaging substrate, such as a sheet of paper, is subjected to heat and/or pressure in order to melt or otherwise fuse the toner permanently on the substrate. In this way, durable, non-smudging images are rendered on the substrates. Fusing of print sheets is also known in other types of printing.
U.S. Pat. Nos. 4,340,807 and 4,372,675 disclose the use of AC “cycle stealing” for precise control of power supplied to a xerographic fusing apparatus.
U.S. Pat. No. 5,826,152 discloses a fuser roll in which the heating elements are disposed within a hollow cylindrical tube inside the roll. Each heating element is independently controllable.
U.S. Published Patent Application 2003/0103778, now abandoned, discloses power control to a dual-lamp fuser, using additional half-cycles as requested power is increased.